Pyrolysis method for increasing limonene production and novel oven to facilitate such method

Abstract

The amount of limonene produced during pyrolysis of scrap tire carcass or polyisoprene rubber can be increased by decreasing residence time of the isoprene gas produced during the thermal degradation of polyisoprene rubber in the high temperature reactor region of an oven. This is achieved by using a novel oven design which permits rapid expansion of the isoprene gas away from the high temperature reactor region of the oven to a cooler region where the gas forms limonene and condenses. This pyrolysis method also decreases the amount of soot produced while increasing the amount of limonene produced. Furthermore, this system readily enables separation of the solid, liquid and gas phases produced during pyrolysis.

We claim: 
     
       1. A method of increasing the production of limonene from the pyrolysis of polyisoprene rubber, comprising the steps of: pyrolytically decomposing polyisoprene rubber to produce isoprene gases in an oven having a central relatively high temperature reactor region and an outer relatively low temperature condensation region surrounding said reactor region wherein the isoprene gases freely expand out of the reactor region and pass from the reactor region to the surrounding condensation region;   condensing said isoprene gases in the condensation region so that isoprene gases dimerize to limonene; and   collecting said limonene.   
     
     
       2. The method of claim 1 wherein the step of condensing comprises cooling said isoprene gases with liquid nitrogen. 
     
     
       3. The method of claim 1 wherein the step of condensing comprises cooling said isoprene gases with water. 
     
     
       4. The method of claim 1 wherein the residence time of said isoprene gases within said relatively high temperature reactor region of said oven is about 1 second to about 5 seconds.